Telephone-transmitter



(No Model.)

W. C. TURNBULL.

TELEPHONE TRANSMITTER.

No. 336,876. Patented F .b. 23, 1886. Ey d 2,

INVENTOR WITNESSES I I N. PETERS, Fhnlc-Lulwgvuphon Waihinghm. o. c.

NITEI) STATES WILLIAM G. TURNBULL, OF BALTIMORE, MARYLAND.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 336,876, dated February 23, 1886.

Application filed July 1, 1885. Serial No. 170,355. (No model.)

To all whom, it may concern:

Be it known that 1, WILLIAM G. TURNBULL, of Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Telephone-Transmitters, of which the following is a specification.

My invention relates more especially to that class of instruments shown in an application filed by me April 18, 1885, No. 162,691.

In the accompanying drawings, Figure 1 is an elevation of the rear face of the transmitting-diaphragm and the electrodes carried thereby. Fig. 2 is an edge view of the same, and Figs. 3 and 4 are similar views showing the device for adjusting the gravity-electrodes.

A is the diaphragm, which is preferably rectangular, and may be made of any suitable material, though preferably of wood.

A series of swinging electrodes, a, are shown as pivoted upon a bar, I), mounted on a bracket, B, secured on the diaphragm, as shown. The bar b is preferably of carbon, though it may be of metal. One end of the primary circuit of the induction-coil is connected with the bar I) by a wire, 40. These swinging pivoted electrodes rest upon a transverse carbon electrode, 0, carried bya bracket, 0, arranged across the diaphragm, preferably about at its center. The electrode 0 is connected by wire 2 with the primary circuit of the induction-coil.

This apparatus is all of the simplest construction, is not liable to derangement, and does not require adjustment. The number of swinging electrodes may be increased or decreased, if desired. The diaphragm may be secured at the top and bottom, as described.

in my application above mentioned, or may be secured at one of its edges only, and is illustrated in Figs. 3 and 4 as secured rigidly at its upper edge to a support, F. The,carbons are all preferably highly polished, so that a smooth clean contact is obtained. \Vith an instrument thus constructed the most delicate sounds, as well as the loudest, will be accurately transmitted without any rattle or grating in the instrument.

I have said that noadjustment of the instrument was necessary, and this is so for all ordinary uses. In order, however. to meet all contingencies and provide for the adjustment of gravity-pressure between the pivoted electrodes and the transverse electrode-bar G,

I have shown an arrangement illustrated in Figs. 3 and 4, but of course any other suitable structure adapted for the purpose may be employed. In this arrangement the bracket B, carrying the bar I), to which the swinging electrodes are pivoted, is itself pivoted in bearings or 1 u gs L L, secured on the diaphragm, as clearly shown. A blunt-ended adjusting screw, D, which bears against the diaphragm,

works through an arm, b on the bracket B. By this means the bar b, to which the pendent electrodes are pivoted, may be moved nearer to or'farther from the diaphragm, so as to vary the pressure with which the pendent electrodes will lie upon the transverse electrodes G. A bent or plate spring, E, secured upon the pivoted bracket B, bears against the diaphragm, as clearly shown in Fig. 4, so as to hold the parts in their adjusted position.

I have found by experiment that a rectangular diaphragm supported rigidly at one edge only operates in a very advantageous manner, and I therefore consider thatfeature important.

I am aware that it has been proposed to suspend or support a diaphragm at one side or edge by yielding or spring support, and do not therefore claim such subject-matter. By mounting the electrodes in a support pivoted near the upper or confined edge of the diaphragm the pivot of the pendent electrodes partakes of a comparatively small amplitude of vibration, while the electrode secured lower down on the diaphragm, being farther removed from the center of vibration, partakes of a much greater amplitude of vibration. Ex-

cellent results are produced by such an organization.

I am also aware that, broadly, a transmitting diaphragm which carries both of the transmittingelectrodes is old.

I am also aware that a transmitting-diaphragm rigidly supported at one end only and elastically held at the other end is old.

In an application for Letters Patent filed by me April 18, 1885, No. l62,69l, I have shown an instrument in part like that herein described; but the subj cot-matter claimed in said application is hereby disclaimed in this case.

I am aware of the telephone of George M. Hopkins,illustrated in the Scientific American of November 10, 1878, in which is employed a rectangular electrode-bar secured upon the diaphragm, upon which electrodes supported by wires fastened to the diaphragm rest by gravity, and I therefore make no claim to such broad ground.

I claim as my invention- 1. The combination of the diaphragm, an elongated electrode-bar having a curved or circular face secured upon the diaphragm, and a series of pivoted freely-swinging pendent electrodes having curved or circular contactfaces, and a pivot-bar supported upon the diaphragm which passes through the upper ends ofsaid electrodes, and on which they have their pivotal bearing, said pendent electrodes resting by gravity upon the transverse electrode secured on the diaphragm, substantially as and for the purpose set forth.

2. The combination of the diaphragm, the series of pivoted pendent gravity-electrodes carried by the diaphragm, the oppositeelectrode or bar secured upon the face of the diaphragm, and adjusting mechanism for simultaneously changing the ,position of the pivots of all of the pendent electrodes, whereby the force of contact between the opposing electrodes is varied.

3. The combination of the diaphragm, the pivoted gravity-electrode carried by the diaphragm, the opposite electrode secured upon the diaphragm, and adjusting mechanism for changing the position of the pivot of the gravity-electrode, whereby the force of contact between the opposing electrodes is varied.

4. The combination of a rectangular diaphragm, a support in which the diaphragm is rigidly connected at its upper edge onlyand is left free to vibrate at its other edges, one or more pendent gravity-electrodes pivoted upon a support carried by the diaphragm near its upper edge, and an opposite electrode or bar upon which the pendent electrodes rest, secured upon the diaphragm below the support in which the pendent electrodes are mounted.

In testimony whereof I have hereunto subscribed my' name;

WILLIAM C. TURNBULL.

Witnesses:

S. A. MORSE, GEO. MOCAFFRAY. 

